Electronic organ sound reproduction apparatus



Aug. 25, 1970 1.. w. PAVIA 3,525,809

ELECTRONIC ORGAN SOUND REPRODUCTION APPARATUS Filed Sept. 11. 1967 /6 FROM 7 ORG/4 N I 20 AMP PRE'AMP 7 Fla. 2

9 30 Z 5 I I I I I 5 I I I I 4 a I'll/Ill!!! N VE N T R LEONARD N. PAVIA United States Patent 3,525,809 ELECTRONIC ORGAN SOUND REPRODUCTION APPARATUS Leonard W. Pavia, Florham Park, NJ., assignor to Pavia- Farny Associates, Morris Plains, NJ. Filed Sept. 11, 1967, Ser. No. 666,760 Int. Cl. Gh 1/02; H04r 1/28 US. Cl. 179-1 8 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION This invention relates to electronic organs and more particularly to the reproduction of low frequency sounds in such organs.

The reproduction of the very low bass notes in an electronic organ is quite diflicult. These are particularly the pedal notes which are to reproduce the sounds of the 16 foot and 32 foot pipes of a true pipe organ. The pipes provide a richness of tone and a delay in the buildup of the sound that simple amplification and direct reproduction by speakers have not matched.

Pipe organs have traditionally been placed in large reverberant rooms, such as churches and auditoriums. 'Iheir present day modern counterpart, the electronic organ is, however, frequently installed in a small room having very little natural reverberatioin effects; in other words, the reveberation time of the small room is so short that no or little natural reverberation occurs. This further deadens the deep bass notes of the organ and prevents a realistic sound impression on the listener.

To overcome these defects various acoustical, electrical, and mechanical schemes have been devised. Some are cumbersome and not suitable to a single organ installation in a small location; thus, various techniques are known that involve separate reverberation rooms or chambers with different acoustic couplings. Other involve relatively complex electronic circuitry for introducing delays in the sound reproduction. While many of these have been relatively successful, they have not fully achieved realistic tones. Further, many of them have suffered from undue complexity, size, and expense.

SUMMARY OF THE INVENTION In accordance with an aspect of my invention, I provide the desired delay and the needed blending of the initial attack of the note with the delayed build up of the note by utilizing two dilferent speakers or pairs of speakers with a unique coupling of acoustic energy between them. Specifically, in one illustrative embodiment a pair of permanent magnet dynamic speakers are mounted on a sound box, which may be open as its end, and connected to the tone generating equipment in the organ for the low frequency notes. Also mounted in this box and on the same face thereof is a second pair of speakers, also of the permanent magnet dynamic type. The speakers may advantageously be identical.

The second speakers serve as acoustic pick ups. While most of the acoustic energy of the first speakers is proice jected out towards the listener, a significant portion of the energy is transmitted through the wood face of the box between the pairs of speakers and is picked up by the second speakers. The percentage of the energy directly radiated by the first speakers can be varied depending on the rigidity of the suspension rims mounting the cones on the face of the sound box.

The voice coils of the second speakers are connected in series and, through a suitable amplifier, to a third pair of speakers mounted ina separate sound box, advantageously fully enclosed. The amplified sound is then radiated by these speakers to the listeners.

I have found tha tthe wooden face of the sound box provides an excellent medium for coupling the desired amount of acoustic energy from the initial reperoduction speakers to the delay or main reproduction speakers. Further, the delay is introduced primarily by the time needed to cause the mass of the pick-up speakers to vibrate, and only secondarily by the distance between the speakers on the face of the sound box. Accordingly, the spacing between the initial reproduction and the pick-upspeakers is not critical. The speakers should be close enough so that there is not an excessive loss of energy in the wood and far enough apart to provide some wood between them and to allow easier mounting of the speakers.

I have also found that while only single speakers need be utilized, providing multiple speakers for the initial sound reproduction and the delay pick up affords better acoustic coupling between the speakers.

In organs incorporating my invention separate speaker arrangements are advantageously provided for the high frequency, the middle frequency, and the low frequency notes, the low frequency speaker arrangement being as herein described. All of the notes of the organ are applied to the initial reproduction speakers; however, the arrangement in accordance with my invention accentuates the low frequency notes.

First, the speakers are advantageously low frequency speakers. Secondly, the mass of the pick-up speaker cones is such that only the low frequency notes will cause the pick-up speaker cones to vibrate. In effect, my acoustic coupling between the initial and pick-up speakers serves as a high frequency acoustic filter.

The mass of the pick-up speaker cone is, as mentioned above, the primary cause of the delay in the build up of the tone. This reproduces very closely the true delay of a pipe organ. In a sense the initiation of vibration of the mass of the pick-up speaker cone can be analogized to the build up of vibration of the mass of air in the larger pipes of the pipe organ. In each instance there is a physical delay involved, rather than the purely electrical delay of some prior low frequency electronic organ sound reproduction systems.

In the same way, I have found that the build up of vibration in the cone of the pick-up speaker, after the transfer of energy through the common wall of the sound box,

'serves to smooth out the tone, improving the actual wave shapes of the notes. There is thus no thin electronic character of the tonal sounds of the organ notes from the reproduction arrangements in accordance with my invention.

While the initial attack of the note is provided to the listener by the initial speakers, most of the sound is actually provided, after the delay build up period, by the second or. main reproduction speakers. The amplification between the pick-up speakers on the first sound box and the main speakers on the second sound box assures this division of the total sound impinging on the listener. However, because the electrical output of the pick-up speakers is smoothed by the action of the pick-up speakers,

3 the final sound from the main speakers is still a close approximation to the true pipeorgan sound and is not hard or electronic in tonal character.

DESCRIPTION OF THE DRAWING FIG. 1 is a schematic drawing illustrating one specific embodiment of my invention; and

FIG. 2 is a simplified sectional view of a dynamic speaker which may be employed with my invention as depicted in FIG. 1.

DETAILED DESCRIPTION Turning now to the drawing, in the specific illustrative embodiment of my invention depicted in FIG. 1 three pairs of speakers 10, 11; 12, 13; and 16, 17 are shown, though either individual speakers or more speakers could be utilized. Thus the initial reproduction speakers 10, 11 could have pick-up speakers, such as 12, 13 on both sides of them and in fact could be surrounded by such speakers if maximum acoustic coupling through the wood is desired between the initial reproduction speakers and the delay pick-up speakers.

Each of the speakers may be of the well-known perma-. nent magnet dynamic type. A simplified sectional view of such a speaker is shown in FIG. 2. As there seen the speaker includes a moving diaphragm 30, generally referred to as the cone, and a suspension rim 31 supporting the diaphragm 30 from the metal basket frame 32 which is physically attached to the supporting frame or box. Often in such speakers the suspension rim is made of a soft material, such as a foam plastic, in order to raise the compliance of the speaker cone; this also serves to prevent the loss of energy through the rim to the supporting structure. In accordance with an aspect of my lnvention, however, a stiff suspension rim is employed, as of the same material as the speaker cone, in order to facilitate the transfer of acoustic energy to the supporting structure. The suspension rim accordingly provides a means for controlling the relative percentages of the acoustic energy directly radiated by the initial reproduction speakers 10, 11 and coupled through the common wooden face to the delay pick-up speakers 12, 13.

Formed with or attached to the cone 30 are a flexible inner cone suspension diaphragm or spider 38 and a coil form 33 on which is placed the coil winding 34. The coil winding 34 on the form encompasses a pole piece 35 and is located in an air gap defined by the pole piece 35 and the metal magnet frame 36 which provides the return magnetic path for the permanent magnet 37. In normal usage the electrical signals are applied to the coil winding 34 causing motion of the coil form 33 and thus of the diaphragm 30. In accordance with an aspect of my invention, the speakers 12, 13, while of the same type as the reproduction speakers 10, 11, are used as pick-ups with the diaphragm 30 of each being vibrated due to the energy coupled to it from the suspension rim 31 and in turn a corresponding electrical signal being generated in the voice coil 34 due to the movement of the diaphragm and specifically of the coil form 33 within the air gap between the pole piece 35 and the edge of the metal magnet frame 36.

While the specific speaker used is not critical to my invention and the three pairs need not be identical, in one specific illustrative embodiment 15 inch woofers were used, specifically Utah Cadence speakers; these speakers have a 20 cycle to 5000 cycle response. It should be noted that the timbre of the tone will depend on the size, shape, and mass of the vibrating cones to a large extent so that various organ effects can be obtained with different speakers or by using pairs of speakers, as shown in FIG. 1, but with the speakers of each pair not being identical. As pointed out above, this arrangement is primarily for the lower frequency notes with other types of speakers or speaker arrangements being provided for the notes of middle and high frequency range.

. V a V 1 4.5 I.

Returning now to FIG. 1, in accordance with an aspect of my invention the initial. reproductionspeakers 10, 11 and the delay pick-up speakers 12, 13 are all mounted on the front face of a sound box 15 which may be open in the back to emphasize its bass frequency response. In one specific illustrative embodiment the box 15 was 4 feet by 4 feet by 1 foot and had a fir plywood front face on which the speakers Were-mounted by the frames 32. The'speak ers face out, towards the listeners.

The coils 34 of the primaryreproduction speakers 10, 11 are connected in series by the leads 20 with the tone generators, not shown, in the organ. My present invention is not dependent on any particular type of tone generators; accordingly, the tone generators may be of any type known in the art for producing organ tones.

The majority of the acoustic energy from the two initial reproduction speakers 1 0, 11 is projected toward the listener in front of the box 15.'In accordance with an aspect of my invention, however, a portion of the energy from the vibrating diaphragms 30 of the speakers 10, 11 is transmitted through their relatively stiff suspension rims 31'into the wooden face of the box 15. This energy is then applied through the relatively stiff suspension rims 31 of the speakers 12, 13 to their diaphragms or cones 30, causing them to vibrate. The resultant vibrations cause voltages to be induced in the coil windings 34 of the pick-up speakers 12, 13. These windings are series connected by leads 21 to a preamplifier 22 and amplifier 23 which may be of known construction. The amplified signals are applied over leads 25 in parallel to the coil windings 34 of the main reproduction speakers 16, 17. By varying the degree of amplification the relative strengths of the initial attack of the tone and the delayed build up of the tone can be altered as desired for maximum sound effect. Just as in a true pipe organ most of the volume of the low frequency tone is provided by the delayed buildup of the note when the full mass of the air in the pipe is vibrated, so in accordance with an aspect of my inventionl provide sufficient amplification so that most of the volume heard by the listener is due to the delayed note from the main speakers 16, 17 rather than due to the initial attack of the note from the initial reproduction speakers 10, 11. Further, because the delay is caused primarily by the time requiredto place the mass of the delay pick-up speaker comes into vibration, the effect is closely similar to the true pipe organ where the delay is caused by the time required to place the mass of air in the pipe into vibration. In the same way'I have found that the reproduced tones from the main speakersvhave had their higher frequency components filtered out by this acoustic coupling and have been smoothed in tonal character and waveform. g, I

Thus, in accordance with embodiments of my invention an initial low frequency output is first heard by the listener, from the initial reproduction speakers. 10,.11; thenvafter a delay, determined primarily by the inertial characteristics of the delay pick-up speakers .12, 13, a smoothed and, louder low frequency output is heard. by the listener from the main reproduction speakers 16, 17. I have found that the combination of the coupling of the energy through the wooden face of the-box and the use of the delay pick-up speakers causes a sound closely resembling that 'of a true pipe orgarig Thus, the main speakers outputs reproduce the initial speakers outputs but with adelay and with smoother tones,

In one specific illustrative emb diment the spacing between the initial reproduction speakers and the delay pick-up speakers was about'l6i inches; the first sound box 15 was 4 feet by'4 feetby' foot; the second sound box 18 was 2 /2 feet by l /z feet by l /z feetrand the amplifier provided about 30 watts of amplification. I have found that the two sound boxes may be placed near each other facing the listener so that the listener is not conscious of two different sound sources However, if only a single box were employed orif the boxes are a'rrangedso that too much of the acoustic energy from the main reproduction speakers 16, 17 is picked up by the speakers 12, 13, then serious problems of acoustic feedback can occur. Similarly, if too much amplification is provided, then the feedback problem is aggravated.

It is to be understood that the above-described embodiment is merely illustrative of the application of the principles of my invention. Various other embodiments and modifications thereof may be made by those skilled in the art without departing from the scope and spirit of my invention.

I claim:

1. In an electronic organ, apparatus for reproducing low bass notes comprising a first sound box including first and second transducers each having a cone and a coil,

means for applying electrical signals to said first transducer coil,

means including a common wall of said first sound box for coupling a portion of the acoustic energy from said first transducer cone to said second transducer cone, said first and second transducers being mounted by said common Wall so that the remainder of said acoustic energy from said first transducer is projected toward a listener,

a second sound box including a third transducer, and

means electrically connecting said second transducer coil to said third transducer, whereby the organ tones are first reproduced by said first transducer and then after a delay by said third transducer.

2. In an electronic organ, the combination of claim 1 wherein said first and second transducers each include a suspension rim supporting said cones from said common wall.

3. In an electronic organ, the combination of claim 1 wherein said means electrically connecting said second and third transducers includes means for amplifying the electrical signals generated by said second transducer before applying them to said third transducer.

4. In an electronic organ, the combination of claim 1 wherein said first sound box is an open enclosure and said second sound box is a closed enclosure.

5. In an electronic organ, apparatus for reproducing low bass notes comprising a first sound box having a wooden face and first and second transducers mounted on said face, each of said transducers including a diaphragm, a suspension rim supporting said diaphragm from said face for coupling acoustic energy between said diaphragm and said face, and a coil,

means for applying electrical signals to said first transducer coil, said first transducer being mounted on said face for projecting most of the acoustic energy output of said first transducer towards a listener,

a second sound box including a third transducer, and

means electrically connecting said second transducer coil and said third transducer.

6. In an electronic organ, the combination of claim 5 wherein a pair of said first transducers are provided and connected in series to reproduce the tones of the organ initially,

wherein a pair of said second transducers are provided to pick up a portion of said acoustic energy of said first transducers from said face, and wherein a pair of said third transducers are provided and said means electrically connecting said second and third transducers include means connecting said pair of second transducers in series, amplifying means, and means connecting said pair of third transducers in parallel. 7. In an electronic organ, the combination of claim 6 wherein said first sound box is an open enclosure and said second sound box is a closed enclosure.

8. In an electronic organ, apparatus for reproducing lower frequency notes comprising initial reproduction speaker means, pick-up speaker means, means for coupling acoustic energy from said initial speaker means to said pick-up speaker means, said coupling means including a common wall of a sound box on which both said initial reproduction speaker means and said pick-up speaker means are mounted,

main reproduction speaker means electrically connected to said pick-up speaker means,

means for delaying the sound reproduced by said main reproduction speaker means with respect to the sound reproduced by said initial reproduction speaker means, said delaying means including diaphragm means in said pick-up speaker means, said diaphragm means having suflicient mass to be set into vibration by said coupled acoustic energy to introduce the required delay, and

amplifier means connecting said pick-up speaker means to said main speaker means to provide the major volume of sound to the listener from the main reproduction speaker means after the initial attack of the sound from said initial reproduction speaker means.

References Cited UNITED STATES PATENTS 2,287,105 6/ 1942 Kannenberg. 2,852,604 9/ 1958 MacCutcheon. 3,145,265 8/ 1964 Yoshiaki Tamura et a1. 3,185,767 5/1965 Olson et a1 3333O X FOREIGN PATENTS 182,790 6/ 1921 Great Britain. 1,346,244 11/ 1963 France.

KATHLEEN H. CLAFFY, Primary Examiner C. W. JIRAUCH, Assistant Examiner U.S. C1. X.R. 841.24 

